A barn may have an elongate interior access hall which leads to a number of animal stalls. The means for access from the access hall to each of the animal stalls may include a door or other openings through which the animals are attended.
Besides permitting easy access to a great number of animal stalls, the access hall provides another function of warming air before it flows into the animal stalls. In a typical barn, air is slowly warmed in stages to take advantage of heat already present in the structure. Air is introduced first into the attic of the barn, then into the access hall, and finally into the various animal stalls.